@Deathhappens in the previous chapter they mention a 1 hour time limit, and QE's line about "a few seconds" seems to imply that Bismarck ran out of time.
So in short, she lost because the time expired.
@truegoddessreincarnation My point was that there's no "lose" condition in hide and seek, but as @arcoviain pointed out this time they had a time limit, hence Biscuit's loss.
@maledetto30 I don't know in what context you spoke, but I suddenly thought about the idea of a Queen x Bismark ship. I don't know why, but it sounds pretty funny.